Email List Hygiene: What, Why, and How 

Email list hygiene cover image with soapy hand holding a sponge

Email list hygiene is the process of removing invalid, outdated, or inactive email addresses from an email list to improve deliverability. It improves your chances of engaging your audience and keeping your email campaigns running smoothly.

Let’s dive deeper into the advantages of maintaining a clean email list and discuss strategies for keeping your list in pristine condition. 

Why Is It Important to Have a Clean Email List?

When you remove harmful addresses from your list, you make sure your marketing messages reach genuinely interested recipients. Doing this has plenty of benefits, such as these: 

clean email list
The best reasons to clean your email list.

Reduce Spam Reports 

Your email list is always changing. People might stop using their current email addresses for all sorts of reasons. Maybe they switch to a new one, change jobs, or decide to switch their email provider. 

If you keep sending emails to these old addresses, you raise the chances of getting flagged as a spammer.

Uninterested subscribers are another reason you might appear as a spammer. This could happen if there’s no clear unsubscribe option at the bottom of your emails or if the process to opt out is too complicated or takes too long.

If you receive spam complaints, you should clean your list and let go of the subscribers who don’t want to stay with your business for any reason. 

At Campaign Refinery, we immediately remove complaining subscribers who don’t use Gmail. However, because Gmail doesn’t reveal the identity of the users who submit a spam complaint, our policy is to require all our senders to keep their complaint rates below 0.1 percent and ideally lower than 0.05 percent. 

Steer Clear of Spam Traps 

Hanging on to old and unused email addresses in your list can lead to a serious problem in your email marketing: hitting spam traps

These are genuine email addresses that were once active but are no longer used by actual people. Mailbox providers take these back and repurpose them as spam traps to catch and block bulk spam senders. 

Sending a single email to a spam trap won’t likely get you into trouble — other than increasing your bounce rate. However, if you don’t scrub your email list, you’ll signal to the ISP that you aren’t following email marketing best practices

The ISP can punish you in different ways, depending on their policies. In the worst-case scenario, you might end up on a blocklist, and clawing your way out of one can be a lengthy and expensive process.

Boost Inbox Placement 

A direct benefit of a clean list is that you’ll get better email deliverability, ensuring your messages land in the inbox where they belong.

Poor deliverability, on the other hand, could be a sign that:

  • You have disengaged subscribers. These people once enjoyed your content but now prefer not to receive your emails.
  • You have a purchased email list. A purchased email list can contain spam traps or subscribers who haven’t opted in. Sending emails to these addresses can increase your bounce rates and spam complaints and hurt your sender reputation. 
  • You don’t have proper domain authentication. While this isn’t directly related to your email list, failing to implement authentication protocols like DMARC, SPF, and DKIM could make ISPs skeptical of your emails’ authenticity. 

Boosting your email deliverability plays a big part in enhancing your sender reputation. The more your emails successfully reach inboxes, the stronger the signals sent to ISPs that you’re a legitimate sender.

At Campaign Refinery, we’re your deliverability partner, committed to ensuring that your messages land in the right inbox. Our sophisticated email list cleaning tool is just the beginning. We provide a comprehensive suite of features designed to optimize your email campaigns from start to finish. 

Elevate User Engagement 

Cleaning your email list doesn’t just boost email deliverability; it also enhances other key email marketing metrics.

Here’s how it helps:

  • Bounce rates. Your bounce rate reflects the number of emails that couldn’t be delivered. Regular email list cleaning reduces the number of unreachable recipients, which leads to better deliverability. 
  • Open rates. If the people on your list don’t like your emails anymore, they’re not going to open them. If your efforts to run re-engagement campaigns fail to win them back, it’s better to focus on those who are really interested rather than keeping a big list of people who ignore your emails. 
  • Click-through rates. Just because someone opens your email doesn’t mean they’ll click on anything inside. The more people actually want to see your emails, the more likely they are to engage with your content. 
  • Unsubscribe rates. Without proper email list hygiene, you keep sending messages to subscribers who don’t want to be on your list. This will increase your unsubscribes and hurt your reputation. Figuring out who’s not interested and removing them before they hit that unsubscribe button can save you from a headache later on.

Maximize Return on Investment 

In email marketing, quality trumps quantity. And no matter how high-quality your content is, it won’t help if your list isn’t. 

When you invest a significant chunk of your budget in email marketing, your primary goal should be to reach and engage as many subscribers as possible. 

Cleaning your email list is key to achieving this. After a thorough clean-up, you might have fewer subscribers, but the ones that stay are more likely to engage with your content. This cleaner list can lead to better interaction with your emails.

Improving your performance metrics, like open and click-through rates, can significantly increase your return on investment (ROI). A more engaged audience can mean better conversion rates, ultimately boosting your marketing success.

Cut Down on Marketing Costs

Your email campaign costs depend on the size of your list because most ESPs charge based on the number of users. 

If you don’t clean your email list, you’ll have to pay for subscribers that don’t benefit your campaign. Even worse, they hurt your KPIs and reduce your ROI. 

When Should You Clean Your Email List?

It’s best to clean your email list every 30 to 180 days, depending on how often your subscribers engage with your emails. We ask all our senders to clean their lists at least every six months and provide the tools to run the process automatically. 

That said, there are specific times when it’s especially important to give your list a thorough check:  

  1. If you’ve been quiet for a while. Not sending emails for some time might mean you may have lost some subscribers’ interest. 
  2. When switching your CRM. Regardless of the reason for switching, using a new CRM is always a good opportunity to clean your list and start fresh.   
  3. After adding new subscribers. Whenever you add new contacts to your list, there’s a high chance that they contain typos or invalid email addresses, especially if you don’t use an email validation service. 
  4. Starting a new job. If you’re new and have inherited an email list, it’s wise to check whether it’s up to date or needs cleaning.
  5. Changing your ESP. This is another chance to start afresh. By cleaning your list, you can ensure you only take the highest quality contacts to the new ESP. 
  6. During a rebrand. If your business has adopted a new direction, your old list may not be relevant. They subscribed to get content that may differ from what you’re going to send. 

How Often Should You Clean Your Email List?

Most experts suggest tidying up your list at least once every six months as a minimum. But according to our list cleaning policy, you should run a re-engagement campaign when you import a list or experience a sudden spike in your subscriber count. 

You should also pay close attention to key indicators like bounce rates, unsubscribe rates, and spam complaints to guide your email list hygiene practices more proactively. 

If you notice sudden increases in these metrics, it’s a good sign that your list needs cleaning, regardless of when you last did it. 

Let’s break down what each of these signs means.

SignWhat it means
High bounce rate A lot of your emails aren’t reaching people, maybe because the addresses are wrong or no longer active.
Low engagement Few people are opening or clicking on your emails, indicating they’re not really interested.
Bot Sign-upsIf you see new sign-ups in a short time in large amounts, there’s a high chance that bots are at work. 
Spam complaintsYou’re receiving a lot of complaints that your emails are unwanted, which is bad news for your reputation.
Signs that it’s time to clean your email list and what they mean

How To Scrub an Email List

Email list hygiene can involve a wide range of actions, each addressing a specific issue. Depending on the severity of the problem, you can perform all or some of the following. 


The first step is to pin down the troublemakers. These include:

  • Invalid addresses. 
  • Spam traps.
  • Role-based addresses. 
  • Inactive users
  • Disengaged subscribers
  • Duplicate addresses
  • Subscribers who mark you as spam

After identifying each prickly thorn, you can take different steps to prune it down. For example, you must delete invalid, inactive, and role-based emails immediately

But you may be able to win over disengaged users through re-engagement campaigns.

Try to Re-engagement Users 

Disengaged and inactive subscribers are different. 

People might not open or engage with your emails for various reasons. Maybe they’re waiting for a certain type of content you haven’t shared recently, or they originally signed up just to get a freebie and weren’t really into your other content.

In these situations, it’s worth trying to win them back with re-engagement campaigns. 

Here’s how you can start:

  1. Define your engagement criteria. Ask yourself, who counts as disengaged? Is it someone who hasn’t opened any of your emails? Or those who open less than 20% of them?
  2. Segment them. Create groups based on their behavior — distinguish between those who never open your emails and those who open but don’t take further action.
  3. Send targeted content. Find out what content resonates with each group. Then, send them tailored content. 

Pro tip: Some people might have signed up just for freebies. Rekindle their interest with special offers, more free products, or exclusive content. 

Remove the Unengaged Ones

If users don’t react to your attempts to win them back, they might need to be removed. However, before you take them off your list, give it one more shot. Send them a final message explaining your plan. 

Let them know you understand if they’re not interested in your emails anymore and offer them a chance to confirm their removal from your list.

Email List Hygiene Best Practices

Identifying and removing unwanted users is one part of email list hygiene. You can keep your list clean by following these best practices. 

Identify Hard and Soft Bounces

When you notice high bounce rates, it’s important to figure out whether you have hard or soft bounces. 

A soft bounce happens if there’s a temporary issue, like the recipient’s inbox is full. You can usually get your message through by trying to send it again later.

A hard bounce, on the other hand, means the email address is invalid, and you’ll never be able to deliver your message to that inbox. These addresses should be removed from your list right away.

If you’re dealing with a soft bounce, try resending the email after some time. But keep an eye on these addresses; if they continue to bounce, you should remove them. For hard bounces, you need to immediately remove the addresses. 

Use Email Validation Services 

An email validation tool helps prevent hard bounces. It checks the email addresses to make sure they’re valid.

These tools look for typos, fake addresses, and disposable emails people often use just for sign-up forms. Depending on which tool you use, you can catch many, if not all, of these problematic addresses and build a valid email list

Never Purchase an Email List

A purchased email list is the most convenient way to hurt your email marketing success. It’s hard to know the origin of these addresses or what issues they might bring.

Most purchased lists come from web scraping, which is the process of extracting emails from websites. While you might get some valid emails this way, these people didn’t agree to receive your emails, so you’ll have a high risk of spam complaints.

Growing an organic email list using a double opt-in process might take a bit of patience and effort, but it really pays off in the long run. 

With double opt-in, people sign up to receive your emails, and they also confirm their subscription through a follow-up email. This extra step ensures that your subscribers genuinely want to hear from you. 

Give Your Audience the Choice

In email marketing, you should get comfortable with letting go. Your subscribers are free to leave if they decide your emails aren’t for them. Still, you should give them the easy option to unsubscribe or manage the frequency of your messages. 

Welcome emails are a great touch for new subscribers. They introduce your business right after someone joins your email list.

If a subscriber realizes they don’t want emails from you, they should be able to opt out immediately. This saves both your time and budget, and it’s better than them marking your emails as spam because they didn’t want them in the first place. An easy way to opt out is also a requirement based on Google’s recent changes to its policies against spam

Opt-down options let users choose to get your messages less frequently. This way, they can stay on your list without feeling overwhelmed. 

Manage Your Content

Content management helps boost engagement and lower unsubscription rates. Crafting useful content starts with a good email segmentation strategy. Tailor your content according to the audience segments to improve engagement. 

Use compelling subject lines to encourage the audience to open your message. But be careful not to use words or phrases that trigger spam filters. 

Beyond just getting your emails opened, the heart of your message must resonate with your subscribers. They must find your email content useful, entertaining, or enlightening. Whether it’s tips related to your industry, exclusive deals, or updates on new products, your emails should provide value that keeps your audience looking forward to hearing from you. 

Use a Reliable Email Marketing Tool

A top-notch tool can handle email list cleaning on its own. You can define automations to run re-engagement campaigns periodically.

But we take the grunt work out of list cleaning at Campaign Refinery. Our state-of-the-art automatic list cleaning tool helps you get rid of all the harmful addresses that undermine your list’s integrity and your sender reputation. 

And the best part? You don’t have to lift a finger to keep your list in tip-top shape. Our software does all the work for you. 

When picking an email marketing service, aim for a deliverability rate of close to 100%. Even 99% deliverability could mean losing access to your subscribers if you’re a high-volume sender. 

With Campaign Refinery, you can expect deliverability that pushes the boundaries. With our advanced deliverability practices, we make sure your emails land right where they should — in your subscribers’ primary inboxes, ready to be opened and read.

Keep Your List Clean on Autopilot with Campaign Refinery

Looking for a way to keep your email list spotless without lifting a finger? Campaign Refinery has got you covered. 

Our automatic list cleaning feature scans your list and removes any addresses that could harm your deliverability rates. This means you can focus more on creating great content, knowing your list is in good hands.

Our tool boasts some of the highest deliverability rates in the market. Why? 

Because we do what other email marketing platforms don’t: 

  • Engagement gamification to boost interaction from your subscribers.
  • Requiring domain authentication from the start to ensure ISPs trust your domain. 
  • Working exclusively with vetted clients to ensure responsible sending behaviors. 

Ready to take your email marketing to the next level? Apply to join us, and let’s make every email count!

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